What is being expressed here is nothing more than aesthetic preference. It is no different morally from saying, "I like Beethoven, but I don't like Wagner." If a woman finds the physiognomic features of the negro to be repellent, she is entitled to that feeling as much as she is entitled to prefer tall men over short men or thin over fat.

Also note that this was a private conversation, overheard by no one, only the machine that recorded it. So they were not "abusing" anyone. Morally, it was no different to having a private conversation in their own homes. But now they have lost their jobs because of it.